ES2217888T3 - FLUIDIZED MILK REACTOR. - Google Patents

Abstract

A fluidized bed reactor includes a furnace defined by side walls, a roof, and a continuous bottom, and has a solid particle bed in the furnace. Vaporizing surfaces form at least two principally vertical chambers. The chambers have a round or polygonal cross section, and extend from the bottom upwards to at least 80% of the height of the furnace. Also, the chambers are spaced away from the side walls of the furnace and are arranged separately within the furnace, for the furnace volume to be free so that the particles move even in the proximity of the chambers.

Description

Fluidized bed reactor.

The present invention relates to an apparatus in a fluidized bed reactor defined in the preamble of the independent clause given below.

The furnace of a fluidized bed boiler comprises an inner section that has a cross section horizontal rectangular and defined by four side walls, a bottom and a roof, in whose inner section the bed material, which contains at least solid particulate combustible material, is  fluidized by means of the fluidization gas introduced through of the lower part mainly by the air required by the Exothermic chemical reactions in the boiler. The walls Oven sides are usually provided with ducts for introduction of at least fuel and secondary air.

The oven walls are usually panels formed by tubes provided in wing, where the energy released from the chemical reactions of the fuel is used to vaporization of water flowing through the tubes. Further, overheating surfaces are usually arranged in the boiler to further increase the energy content of the steam.

When the goal is to manufacture a boiler of high capacity, a large reaction volume and a large volume are needed Vaporization and overheating surface. The basal area of The boiler is directly proportional to the capacity of the boiler based on the volume required and the speed of the fluidization air. Since, at least from the point of view structural, it is harmful to have a very long oven bottom and narrow, also the height of the boiler and the width of its bottom they have to be increased to have a vaporization surface Large enough on the side walls. Increase Significantly height can lead to problems structural and increase the width makes it more difficult to arrange a uniform supply of fuel and secondary air. To resolve these problems, additional structures can be arranged within of the oven to increase the vaporizing surface of the boiler.

The most conventional way to increase Vaporization surfaces of the boiler is to adopt a provision such that the separation walls extend from a wall side of the boiler to another. A provision of this class is reveals, for example, in U.S. Patent 3,736,908. Special openings have to be arranged in said walls of separation to ensure uniformity of materials and processes in various parts of the boiler. Even when they exist numerous openings of this class is difficult, however, in the boilers that have separating walls achieve homogeneity required for optimal performance and minimization of emissions environmental. These problems are more evident in the corners lower boilers which are the most critical points with regarding the uniform performance of the boiler and the number of these corners is inevitably increased by the existence of partition walls extending from a side wall to other.

The flow of water circulating in two phases in the vaporization tubes is a difficult phenomenon to control in complicated geometric configurations. From this point of view, A problem associated with simple partition walls is that, at Unlike the side walls of the boiler, there is a thermal energy transfer to the wall tubes from both sides. To obtain the vaporization and circulation of water in the partition walls in equilibrium with vaporization in the side walls, the size of the walls tubes separators have to be larger or have to be located more densely than on the side walls. Arrange walls separators, which can be relatively thin considering their height, which extend from the bottom of the oven to the part superior, it can be difficult in a high boiler with a view to get enough stiffness for the walls.

It is known by the prior art to provide also the refrigerated partition walls with various kinds of necessary elements for the operation of the bed boiler fluidized For example, U.S. Patent 5,678,497 and WO 98/25074 refer to provisions where means for secondary air supply are attached to the walls refrigerated separators.

Instead of separating walls, it is also known to arrange other kinds of auxiliary structures within the oven used to produce steam and possibly also to Other operations U.S. Patent 5,070,822 is refers to an arrangement, in which a particle separator concentric cylindrical, whose outer shell is formed by a thermal transfer surface, is arranged within a cylindrical oven At the bottom of the same structure there are also elements for the introduction of fuel into the oven. U.S. Patent 4,817,563 refers to a arrangement, in which upwardly cooled conical structures, arranged at the bottom of the oven covering 40 to 75% from the bottom of the oven, they are used for fuel supply and secondary air U.S. Patent 4,947,803 is refers to a fluidized bed reactor where they are arranged cylindrical contact units cooled. However, all these provisions are quite expensive and less applicable in a Large-scale fluidized bed boiler and the surface of auxiliary vaporization provided by these provisions is less significant

The object of the present invention is a new perfected apparatus in a fluidized bed reactor.

Therefore, an object of the present invention is to provide a new technical solution, by means of which fluidized bed boilers of various sizes may be provided with vaporization surfaces and are resolved or minimized problems and defects previously mentioned in the prior art.

A special object is to provide a system to arrange vaporization surfaces in large boilers of fluidized bed

Another object is a simple structure apparatus and high performance / cost ratio that eliminates or minimizes previous problems

Likewise, an object of the present invention is provide auxiliary vaporization surfaces in a boiler of fluidized bed so that it is possible to create, in all the vaporization surface, vaporization conditions Similar.

Another object of the present invention is provide a fluidized bed reactor, in which it is obtained a good mix of uniform materials and process conditions in the oven, despite the auxiliary vaporization surfaces and therefore, high combustion performance is achieved and A reduction in emissions.

To meet these objectives, it is characteristic of the apparatus in a fluidized bed reactor, according to the present invention, which is described below in the part characterizing the independent claim.

The invention is especially applicable to a fluidized bed boiler. When the invention is applied, the Vaporization surfaces are arranged in the bed boiler fluidized so that cameras, mostly vertical, are arranged inside the oven. In this descriptive report of the invention and in the claims, the term "camera" is refers to a structure surrounded by walls, within whose structure forms a mainly closed gas volume. The walls are usually made of straight water tubular panels formed with water pipes in wing. The height of the chambers in a boiler of fluidized bed is usually the same as the oven height, preferably at least 80% of the oven height. The cameras they extend, in a preferable embodiment, from the bottom of the oven to your ceiling, where they can be used to reinforce the oven.

When a provision is used according to the In the present invention, a desirable amount of chambers in the furnace of the fluidized bed boiler and so Therefore, the size of the boilers is not limited by vaporization surfaces required. In a small boiler, there may preferably be, for example, one or two cameras according to the present invention. In a large boiler, there is, in a preferable embodiment, a plurality of, for example, three, four, six, eight and even up to ten or more cameras The cameras can be arranged one after another, in two or several rows, or in another order considered preferable in each particular case. In a fluidized bed boiler, it is preferable than 20 to 70%, and more preferably 40 to 60%, of the Vaporization surface of the boiler is arranged in the cameras according to the present invention.

The cameras according to the present invention usually be of two-dimensional cross section, where two opposite walls are separated a short distance from each other. Both sides of the opposite vaporization surfaces are practically not heated, but only one side. Therefore, the conditions for all vaporization surfaces, that is, for the vaporization surfaces of the boiler walls and of the walls of the chamber, they are mainly the same. For the therefore, the structures of water pipes can be sized from the same way as the water pipe structures of the walls boiler exteriors. This is an important advantage with regarding the steam circuit sizing and the management of risk, especially in the case of single pass boilers.

Within the boilers there is usually a section lower that is usually used for several purposes. For example, support structures required by mechanical strength structural cameras can be built within the own cameras, so cameras can be done considerably high, if necessary. The support structures arranged in the cameras can also be used to reinforce the resistance Structural mechanics of the furnace of the complete boiler.

The cameras according to the present invention usually have a shape such that its cross section is approximately constant at most oven height, preferably at least 50% of the oven height. The structures auxiliaries required by the various reactor functions of fluidized bed or boiler, especially when attached to the top and bottom of the cameras can change without However, the shape of the camera at that point.

Typically the fluidized bed boiler can be provided with more vaporization surface without the need for Divide the oven into separate parts by walls. The bottom of full oven is, except for separate chambers, of nature continues. Therefore, the process that takes place within of the oven, which is usually the combustion process, does not need split into parts, but the bed material can be shift almost freely within the full volume of the oven.

The horizontal cross section of the cameras it is preferably complex; that is, seen from within the chamber, the angles formed by its adjacent walls are smaller than 180 degrees. Also, the cameras are usually, in a preferable embodiment, separated from the side walls of the oven. In this way, the cameras do not form interior corners in the oven, which could be problematic with respect to the mixture, but all the corners created by them are corners exteriors as seen from the oven direction. For the therefore, most of the volume, even in the vicinity of cameras, is free for the displacement of particles and their movement is practically not restricted. Not to restrict the furnace particle movement, each diagonal of the chambers it is preferably not more than 60%, and more preferably not more than 50% of the parallel diagonal of the oven.

They can also be added to the cameras of vaporization, according to the present invention, other structures and functions related to the fluidized bed boiler. The more preferable means to supply secondary air are arranged in the cameras. They can also be arranged in medium chambers for the introduction of fuel or limestone, where the transfer of fuel or limestone inside the chamber is, in a preferable embodiment, performed by pneumatic means or by means of an advance screw arranged in an inclined position. In a preferable embodiment, the chambers may be formed. by planar tubular water panels, even when, in some cases, it is advantageous to use cameras that have a section round cross. The cross section of the chamber has, in a preferable embodiment, the shape of a polygon and more preferably, a rectangle. The cross section of the rectangle can be square, but preferably it is elongated so that the proportion of the respective side lengths long and the short side be at least two. A camera that has a elongated cross section is advantageous, since provides a large vaporization surface without an addition significant to the total area of the bottom of the boiler. To arrange various structures and devices in the cameras, the distance between its opposite walls must be, in one embodiment preferable, at least 0.5 meters and more preferably 1 meter As minimum.

Also, a particle separator can be preferably arranged in one or several chambers of the boiler of fluidized bed, where at the top of the chamber are arranged one or more openings, through which the gas of Exhaust generated in the oven and the material of the entrained bed They can flow into the inner section of the chamber. A separator of impacts or a cyclone separator is disposed within the chamber to separate the exhaust gas from the bed material, which drag. The clean exhaust gas is discharged through the part upper chamber and separate bed material is made go back to the oven

According to a preferred embodiment of the invention, the chambers containing a particle separator are sectional transverse square, in which the inlet ducts from the oven are arranged in one or several side walls next to The corner of the camera. In a more preferable embodiment, a entrance is arranged on each side wall of the chamber square.

Cameras containing a separator particles may also have an elongated cross section, in where two or several vortices, close to each other, are generated in a chamber through the entry and exit openings. They can there are internal separating walls in the chamber between the various  Vortices or the latter may be in the same space.

Also, the heat transfer chambers they may preferably be arranged at the bottom of the chambers, for example, for steam overheating. He Hot bed material penetrates the chambers of heat transfer either directly from the fluidized bed surrounding, either from return ducts of the separator particles arranged in the chamber. The cameras of heat transfer arranged inside the chambers reduces the need to have the heat transfer cameras connected to the side walls of the oven, where more surface area of free side wall, for example, for the introduction of fuel.

Also, overheating surfaces they may preferably be arranged connected to the cameras, for example, overheating surfaces of the wall type in to. In this case, the interior of the cameras is provided with connecting pipes for steam, from where the pipes Overheating are carried out of the chamber wall, by example, baked, so that the tubes and tubular panels continue up in the vicinity of the wall and end in the headers arranged above the roof of the oven.

Arranging a necessary number of cameras separated in the boiler, the distance between two points of Adjacent introduction, for fuel and secondary air, can have a desired length anywhere. Thus, homogeneous process conditions can be arranged in a way brand new even in the furnace of an older boiler dimensions, when using an arrangement according to this invention.

The vaporization surface may be arranged, in a necessary extension, even in a boiler of large fluidized bed when using an arrangement according to the present invention without increasing oven height or damaging The mixture of the material. Adding auxiliary structures in the chambers according to the present invention, the rigidity of the boiler and the homogeneity of materials and process can be improved and increase the free space on the side walls of the boiler.

The invention is described below with reference to the accompanying drawings in which:

Figure 1 illustrates, schematically, a vertical cross section view of a bed boiler circulating fluidized provided with example chambers according to the present invention;

Figure 2 illustrates a sectional view horizontal cross section of the boiler of Figure 1;

Figure 3 illustrates, schematically, a vertical cross-sectional view of a boiler vaporization according to the present invention, where a overheating surface;

Figure 4 schematically illustrates a vertical cross-sectional view of the bottom of a exemplary vaporization chamber according to the present invention, in the that a heat exchange chamber is attached,

Figure 5 schematically illustrates a horizontal cross-sectional view of another bed reactor fluidized comprising chambers according to the present invention, including overheating surfaces, chambers of heat exchange and particle separators;

Figure 6 illustrates, schematically, a vertical cross-sectional view of a third bed reactor fluidized including exemplary chambers according to the present invention;

Figure 7 illustrates, schematically, a horizontal cross-sectional view of a fourth reactor of fluidized bed

Figures 1 and 2 illustrate, schematically, a fluidized bed reactor having an exemplary structure according to the present invention. The main parts of the boiler 1 are the oven 2 and the particle separators 3. The oven 2 is defined by the side walls 4, a bottom 5 and a roof 6. The oven 2 is provided with ducts 7 for fueling and other bed materials, for example, sand and lime. The bottom of the boiler is provided with means 8 to supply air for fluidize the bed material. The bottom of the oven is also provided with ducts 9 to supply air secondary.

Through air deliveries to the boiler, fuel combustion is maintained. Ashes and materials from the bed they are discharged together with the fluidizing air and the exhaust gases through conduits 10 to separators 3, where most of the solid material separates from the gases of escape and return through a return tube 11 to the part bottom of the oven 2.

The side walls 4 of the oven are formed by water pipe panels consisting of water pipes provided in wing in a manner known in this technique and not illustrated in detail in the figure. The energy released from the fuel combustion is used to vaporize the water that circulates through the water pipes of the side walls.

Inside the oven there are 12 chambers according to the present invention made of walls of water pipes that extend from the bottom of the oven to its top. The walls 13 of the chambers are made of water pipe panels, which are attached to feeding tubes 14 below the oven and to tubes of header 15 above the oven. Inside the cameras there are means illustrated by way of example 16, 17 for supplying air secondary and fuel to the central part of the oven.

Figure 2 illustrates the cross section horizontal of the fluidized bed boiler as illustrated in the Figure 1. In the chamber, as illustrated in Figures 1 and 2, There are nine cameras in total, mainly in two rows. He number and location of the cameras could also be different from  those illustrated here. They could be, for example, all in one row or there could be more than two rows.

In Figure 2 the cross section of the cameras is a rectangle, where the proportion of the respective Long side and short side lengths are three or five. This proportion could also be another, even more than five less than three. In some cases, the cameras could also be sectional transverse square.

In Figure 2, the smallest cameras 12a they are provided with a symbolic mark of a structure 18 that reinforces the rigidity of the cameras and the larger camera 12b has a mark of a larger structure 19 that especially reinforces the oven stiffness.

The total number of cameras arranged in the oven could vary even within a very wide range, if It was necessary. In a small boiler, it could exist, for example, only one or two chambers, but in a larger boiler there may even be more than ten cameras.

Figure 3 illustrates how the surfaces of Overheating 20 of the wing type walls can be added, for example, to the vaporization chambers 12 arranged in the fluidized bed boiler as illustrated in Figure 1. The Overheating surfaces are made in tubular panels where the steam that is going to overheat circulates from the pipes of feed 21, arranged inside the vaporization chamber, to the header tubes 22 arranged above the roof of the oven.

As illustrated in Figure 4, the camera heat transfer 30 is disposed inside the vaporization chamber 12. The hot bed material flows from bed 2 through an entrance 21 to the chamber. Be maintains a slow fluidization in the chamber by means of devices 32, where the bed material cools on the heat transfer surfaces 33. The material is discharged to through an opening 34 at the bottom of the chamber to a conduit 35, where it circulates upwards by means of fluidization  generated by devices 36 and flows through an outlet 37 returning to the oven 2. The structure of the chamber of heat transfer arranged in the vaporization chamber could be also different from that illustrated here.

Figure 5 illustrates a cross section vertical of the furnace 2 of a fluidized bed boiler, where two types of vaporization chambers 12c, 12d are arranged. The first part of the vaporization chambers 12c is provided with 20 superheat surfaces and heat transfer chambers 30 as illustrated in Figures 3 and 4. The second part of the 12d vaporization chambers is provided with a separator particles 40. The particle separator as illustrated in the Figure 5 has a rectangular cross section, the ratio of the long side to the short side of approximately two. There are two gas outlets 41 at the top of the separator and an opening in the bottom, through which the material separately can be returned to the oven.

The gas that carries the particulate material is leads to the separator, so that the gas stream enables also the generation of a vortex. Therefore, the ducts 42, 43 to direct the gas stream perpendicular to the wall of the separator are, in a preferable embodiment, arranged in the  point where the direction of the vortex flow is out from Wall. Oblique inlet ducts 44 may be arranged parallel to said vortex also in other parts of the walls lateral.

In some cases, it can be advantageous arranging a separating wall 45 between two vortices of the separator of particles 40. The proportion of the sides of the section transverse of the particle separator could also differ from the  illustrated in Figure 5. The separator could be, for example, of square cross section.

Figure 6 illustrates a third embodiment preferable of the invention, where the vaporization chamber 12, starting from the bottom 5 of oven 2 does not continue to the ceiling 6, but curves before reaching the ceiling and penetrates through the side wall 4a of the oven next to the roof of the oven. This class of disposal could be advantageous in some cases with with respect, for example, to the control of thermal expansion. Of the same way, the bottom of the camera could bend also so that it penetrates through the side wall.

In addition, as illustrated in Figure 7, a horizontal cross section of a fluidized bed reactor, where the chambers according to the present invention are arranged in the oven, so that its wall surfaces are not parallel to the oven wall surfaces, but form an angle Approximately 45º between them, that is, take a form rhomboid.

Claims (24)

1. Fluidized bed reactor comprising a oven (2) defined by side walls (4), a roof (6) and a background (5) and gifted:

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of a bed of solid particles and

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of surfaces of evaporation that form at least two chambers mainly vertical (12), the cameras having a cross section round or polygonal and

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extending from the bottom (5) up at least 80% of the height of the oven,

characterized because

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said fund (5) is continuous and

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those cameras are separated from the side walls of the oven arranged separately inside the oven, so that the volume of the oven is free so that the particles move even in the vicinity of these cameras.

2. A fluidized bed boiler according to claim 1, characterized in that said chambers extend from the bottom of the oven to the ceiling (6) of the oven. 3. The fluidized bed boiler according to claim 1, characterized in that 20 to 70% of the evaporation surfaces of the boiler are arranged in said chambers. 4. A fluidized bed boiler according to claim 1, characterized in that 40 to 60% of the evaporation surfaces of the boiler are arranged in said chambers. 5. A fluidized bed boiler according to claim 1, characterized in that there are more than two of said mainly vertical chambers. 6. A fluidized bed boiler according to claim 1, characterized in that said chambers are arranged in at least two rows of the oven. 7. A fluidized bed boiler according to claim 1, characterized in that the cross section of said chambers is convex. 8. A fluidized bed boiler according to claim 7, characterized in that the cross section of said chambers is rectangular. 9. The fluidized bed boiler according to claim 1, characterized in that the cross section of said chambers is almost constant at least 50% of the oven height. 10. The fluidized bed boiler according to claim 1, characterized in that the length of each diagonal of the horizontal cross-section of said chambers represents more than 60% of the length of the parallel diagonal of the furnace. 11. A fluidized bed boiler according to claim 8, characterized in that the distance between the opposite walls of said chambers is at least 0.5 meters. 12. A fluidized bed boiler according to claim 1, characterized in that means for introducing secondary air are disposed within said chambers. 13. The fluidized bed boiler according to claim 1, characterized in that means for introducing a fuel are disposed within said chambers. 14. A fluidized bed boiler according to claim 1, characterized in that an overheating surface is disposed within said chambers. 15. A fluidized bed boiler according to claim 14, characterized in that the superheater disposed in said chambers is of the wing wall type. 16. The fluidized bed boiler according to claim 1, characterized in that a heat transfer chamber of the boiling fluidized bed type is disposed within the lower part of said chamber. 17. The fluidized bed boiler according to claim 1, characterized in that a structure that reinforces the stiffness of the chamber is disposed within said chambers. 18. A fluidized bed boiler according to claim 1, characterized in that a structure that reinforces the stiffness of the furnace is disposed within said chambers. 19. A fluidized bed boiler according to claim 1, characterized in that a particle separator is arranged inside one or more of said chambers. 20. A fluidized bed boiler according to claim 19, characterized in that the particle separator is of the cyclone separator type. 21. Fluidized bed boiler according to claim 20, characterized in that the cross section of the particle separator is rectangular. 22. Fluidized bed boiler according to claim 21, characterized in that the cross section of the particle separator is square. 23. A fluidized bed boiler according to claim 21, characterized in that the length of the longest side of the cross section of the particle separator represents at least twice the length of the shortest side. 24. A fluidized bed boiler according to claim 23, characterized in that a vertical partition is disposed within the particle separator.